Is there a way to reserve project hours for certain projects?

So, I was wondering if there’s a way to reserve some of your active hours for specific sites. Ex, let’s say I’ve got this ‘main site’ and then another site that doesn’t matter as much if it’s active or not. Is there a way to reserve hours for sites and/or limit hours on sites?

At the moment there isn’t, but that sounds like an interesting feature request.